The use of drive means to enable one or more vehicle wheels to be self-propelled and move the vehicle along a ground surface without reliance on another source of motive power is known in the art. A variety of vehicles, ranging from forklifts to automobiles, trucks, and aircraft, can be moved in this manner. The kinds of drive means proposed to propel vehicle wheels can also vary. Most drive means currently used to propel vehicle wheels are electric motors. When a wheel drive means is driven by gearing, a clutch is often included in the drive system to allow engagement and disengagement of a gear assembly. Wheel drive means, gear assemblies, and clutch assemblies must be located where these structures can effectively power and drive one or more vehicle wheels and thus propel the vehicle effectively on the ground. Locating all of these structures within the dimensions of the vehicle wheel enables the wheel to be as compact as possible, yet still function effectively.
The use of a drive motor structure mounted in connection with a vehicle wheel to rotate the wheel and drive the vehicle has been proposed. The use of such a drive motor structure should, ideally, move a vehicle without reliance on the vehicle's main source of motive power, whether the vehicle is an automobile, aircraft, or other vehicle. Such structures have been described in connection with aircraft. In U.S. Patent Application Publication No. US2010/0065678 to Kiyosawa, a self-propelled wheel apparatus for an aircraft with a wave gear drive and a motor coaxially linked to an aircraft wheel axle with a one-way clutch to move an aircraft on the ground is described. The gear drive, motor, and clutch are all positioned coaxially adjacent to an aircraft landing gear wheel. U.S. Pat. No. 7,445,178 McCoskey et al describes a drive motor associated with aircraft nose landing gear wheels intended to drive aircraft on the ground that includes a dual cone clutch and a planetary gear system with an actuation screw mounted partially within a wheel and partially between the wheel and a landing gear strut. Neither Kiyosawa nor McCoskey et al suggests mounting all wheel drive structures completely within the axial or other dimensions of an aircraft wheel, nor do they suggest mounting wheel drive structures other than externally of an axle supporting a wheel to be driven.
Published United States patent applications, including U.S. Patent Application Publication Nos. US2006/0273686 to Edelson, US2007/0282491 to Cox et al, US2009/0152055 to Cox, US2009/0261197 to Cox, International Patent Application Publication No. WO 2008/027458 to Cox et al, and British Patent No. 2457144, owned in common with the present invention, describe aircraft drive systems that use electric drive motors to power aircraft wheels and move aircraft independently on the ground. When gear and clutch assemblies are used with such drive systems, these assemblies may be mounted within the space defined by the wheel dimensions externally of the landing gear wheel axle. The arrangement of these clutch assemblies and drive systems does not maximize available space, however.
A need exists for a wheel drive assembly, including drive means, a gear assembly, and a clutch assembly, operable to drive a vehicle wheel independently on the ground that can be located completely within a space defined by the dimensions of the vehicle wheel, wherein at least the clutch assembly is designed to be positioned within the vehicle axle, so that the wheel drive assembly is as compact as possible, yet still functions effectively to drive the vehicle wheel and move the vehicle on the ground.